Fix the null pointer for operation json list.

modules/charon-core/src/main/java/org/wso2/charon3/core/encoder/JSONDecoder.java

@@ -746,13 +746,26 @@ private ComplexAttribute buildComplexValue(AttributeSchema attributeSchema,
      */
     public ArrayList<PatchOperation> decodeRequest(String scimResourceString) throws BadRequestException {
 
-
         ArrayList<PatchOperation> operationList = new ArrayList<PatchOperation>();
         try {
             //decode the string into json representation
             JSONObject decodedJsonObj = new JSONObject(new JSONTokener(scimResourceString));
             //obtain the Operations values
             JSONArray operationJsonList = (JSONArray) decodedJsonObj.opt(SCIMConstants.OperationalConstants.OPERATIONS);
+
+            //check if operationJsonList is null
+            if (operationJsonList == null) {
+
+                //throw appropriate exception based on the key check
+                if (decodedJsonObj.has(StringUtils.lowerCase(SCIMConstants.OperationalConstants.OPERATIONS))) {
+                    throw new BadRequestException("Invalid JSON schema.", ResponseCodeConstants.INVALID_SYNTAX);
+                }
+
+                //if the key with lowercase name does not exist, throw this exception
+                throw new BadRequestException(ResponseCodeConstants.INVALID_SYNTAX);
+            }
+
+
             //for each operation, create a PatchOperation object and add the relevant values to it
             for (int count = 0; count < operationJsonList.length(); count++) {
                 JSONObject operation = (JSONObject) operationJsonList.get(count);